This invention relates to an arrangement to permit VLF (very low frequency) communications with a submerged submarine and more particularly to a buoyant cable antenna arrangement for such communications.
In recent years there have been two major systems which permit VLF communications with a submerged submarine. One such system includes a buoyant hydrodynamic shaped buoy towed by a submerged submarine. In this system VLF reception is achieved through the combination of a crossed loop antenna located in the nose section of the buoy and an electro-mechanical tow cable linking the buoy with the submarine. The radio signals are received by the crossed loop antenna and then travel through the tow cable to the receiving equipment in the submarine.
The second system employs a floating cable antenna that is unreeled from a submerged submarine, floats to the surface and receives the radio signals which travel through the length of the floating cable into the submarine.
Although both of the above-mentioned systems have functioned satisfactorily they are however limited in certain areas. For example, in the floating cable antenna system there is a limit of submarine keel depth and maximum speeds at which the floating cable antenna system is operational. The buoy system on the other hand is operational at a greater submarine keel depth when traveling at the same maximum speeds. If, however, the depth of the submarine is decreased, the speed of the buoy system can be increased which is an important factor when considering strategic maneuverability. VLF reception is better in the floating cable antenna system due to the fact that the cable floats on the water surface whereas in the buoy system the buoy is towed below the surface of the water where reception can be erratic depending on sea state conditions and buoy stability.
Although there are other shortcomings and advantages of both the above-mentioned systems, it can be seen from the above that each system has its advantages.